A novel magnetic Fe–Co–Zn composite as an effective and recyclable adsorbent for the removal of dyes from wastewater

Abstract

Removal of pollutants from wastewater has always been a concern. Activated carbon-based adsorbent materials are promising for the removal of organic pollutants from the aqueous phase owing to their rich pore structure and high chemical activity. However, the majority of activated carbons (ACs) exist as micro-crystalline powders, making their segregation and recycling complicated. Therefore, in this work, a new magnetic adsorbent (AC-CN-Fe-Co-Zn) was prepared by impregnating activated carbons with urea (CN) and metal salts (Fe, Co, and Zn), followed by calcination, for the adsorption of methylene blue (MB) and acid blue 80 (AB80) from aqueous solutions. The ensuing series of experiments were conducted to investigate the effects of pH, binding time, temperature and initial concentration on the adsorption behaviors of MB and AB80 by AC-CN-Fe-Co-Zn. Results indicated that the inorganic ions in the magnetic material displayed excellent dispersion on the surface of the carbon material, and the pseudo-second-order kinetic model accurately fitted with the adsorption data. Thermodynamic adsorption curves were consistent with the Langmuir model. The adsorption mechanism involved the critical contribution of the hydrogen bonding interaction, π–π interaction, pore adsorption, and electrostatic attraction. The maximum adsorption capacities of MB and AB80 were 83.40 mg g⁻¹ and 35.36 mg g⁻¹, respectively. The eradication efficacy of MB and AB80 remained high after 5 repeated applications. Results confirmed that the comprehensive properties of AC-CN-Fe-Co-Zn make it an excellent and efficient adsorbent for the removal of dyes. This work provides a new insight into the synthesis of high-efficiency adsorbents for the removal of dye pollutants.